Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
s=[list(input()) for _ in range(h)]

q=[(0,0)]
s[0][0]=0
dxy=[(1,0),(-1,0),(0,1),(0,-1)]
while q:
    x,y=q.pop(0)
    for dx,dy in dxy:
        nx,ny=x+dx,y+dy
        if not 0<=nx<w:
            continue
        if not 0<=ny<h:
            continue
        if s[ny][nx]=="#":
            continue
        if s[ny][nx]==".":
            s[ny][nx]=s[y][x]+1
            q.append((nx,ny))
        else:
            continue
if s[h-1][w-1]=="." or s[h-1][w-1]=="#":
    print(-1)
else:
    kuro=0
    for i in range(h):
        kuro+=s[i].count("#")

    print(h*w-s[h-1][w-1]-1-kuro)